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Friday, December 25, 2009

Using my hacked espresso machine

I recently bought a Saeco Titan coffee grinder, and have been very pleased with the consistency and control of the grind size. I had to hack it (of course) to get the grind fine enough for espresso, but it's working, and it seems like a well-built machine.For info on adjusting the grind size outside of the factory settings, see here:http://www.ineedcoffee.com/07/hack-starbucks-grinder/The Saeco Titan, Starbucks Barista, and Solis 166 are all the same machine. There are probably a few other rebranded models out there too.

A few years ago, I took a Krups "steam-powered" espresso machine and retrofitted it with a temperature control and air pump. The air pump pressurizes the air above the hot water in the heating tank, and the water is conveyed from the bottom of the tank to the group head. Thus, the air pressure will be the same as the water pressure. This differs from commercial espresso machines which use a water pump to move a specific volume of water through the coffee. The pressure is determined by the resistance the coffee poses to the set flow rate of water.

The temperature control was hacked from an old meat thermometer. It has a very basic proportional control. The air pump was salvaged from a 12V tire-inflator compressor. The large circuit board is a computer power supply that provides high current 12V to the compressor.

About 14g of coffee, finely ground and tamped down into the portafilter.

I realize my shot is a little fast and pours out too violently. I'm still figuring out the ideal pressures and valve opening sequences for this machine. Since this is essentially a constant-pressure machine and commerical machines are constant flow-rate, there may always be some differences in how the coffee is made.

Lots of crema. This demitasse holds about 2 oz with additional headroom for the crema. It tastes great! I am very happy with the espresso that it makes. On cold days, I usually take a sip from the demitasse, then dump the rest into a large mug of hot water for an Americano.

5 comments:

Ben, I love your blog. Having been a Batista for many years in an old school classic Italian technique driven shop (unlike Starbucks assembly line no skill needed), I can tell you that a fantastic shot comes from modifying the grind and preheating the head.

A few years ago, I took a Krups "steam-powered" espresso machine and retrofitted it with a temperature control and air pump. The air pump pressurizes the air above the hot water in the heating tank, and the water is conveyed from the bottom of the tank to the group head. delonghi esam3300 refurbished

Remember that 9 atmospheres of pressure is considered ideal (unless you want to ride pressure curves), and adjust your grind size to restrict the flow to the point where it takes about 28 seconds for 2 fl oz to pass through 14 grams of espresso. Donts forget to tamp and polish without knocking the portafilter, and Boom! You now have a restretto. Coffee degasses CO2 for 2 weeks after roast, and that CO2 held under 9 atmospheres of pressure goes into solution in the water as carbonic acid. This acid acts on the coffee solids and flavor components changes the chemical constituency of the coffee espresso liquid. As the liquid passes through the sieve, the CO2 (stored as carbonic acid) becomes polyphasic colloidal foam, making crema! The liquid and everything it touches needs to be held close to the temperature of the boiler else it sours (sometimes in as little as 30 seconds). This souring is halted by pouring the espresso into another liquid of greater of equal volume.